US6275678B1 - Method and apparatus for determining an operating point of a non-linear amplifier of a communication channel - Google Patents
Method and apparatus for determining an operating point of a non-linear amplifier of a communication channel Download PDFInfo
- Publication number
- US6275678B1 US6275678B1 US09/213,557 US21355798A US6275678B1 US 6275678 B1 US6275678 B1 US 6275678B1 US 21355798 A US21355798 A US 21355798A US 6275678 B1 US6275678 B1 US 6275678B1
- Authority
- US
- United States
- Prior art keywords
- signal
- pseudo noise
- payload
- level
- carrier signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/20—Monitoring; Testing of receivers
- H04B17/24—Monitoring; Testing of receivers with feedback of measurements to the transmitter
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
Definitions
- This invention relates to a method and an apparatus for determining an operating point of a non-linear amplifier of a communication channel, especially a transponder in a communication satellite under load.
- a non-linear high power amplifier In high frequency communication channels, a non-linear high power amplifier must often be driven at its saturation point in order to obtain the maximum possible output.
- a signal from an uplink station on the ground is received by an antenna, converted in frequency, filtered in an input multiplexer, and amplified by a driver limiter amplifier and a high power amplifier before being filtered in the output multiplexer and retransmitted to the ground.
- the high power amplifier In order to provide a sufficient signal everywhere within the satellite footprint, the high power amplifier must be driven in its saturation point, i.e. the point of maximum in the non-linear transfer curve representing output power vs. input power, as for example shown in FIG. 6 a.
- the driver limiter amplifier is a preamplifier and can be set to run in one of two modes. In linear mode, it acts as a simple linear amplifier. In limiting mode, it provides the function of an automatic level control (ALC). The DLA is normally operated in limiting mode in order to compensate short term level variations due to weather influences. In limiting mode, the DLA shall always provide the same output power to the high power amplifier (HPA), such that the HPA is permanently operated in saturation.
- HPA high power amplifier
- the DLA Even if the DLA is able to maintain the HPA in saturation if the power received from the uplink ground station is below specification, it is very important that the uplink ground station power is kept on a high level since if the DLA has to compensate for uplink power, the overall signal to noise ratio (SNR) is decreasing, as this is mainly driven by the SNR in the earliest stage of the signal path which is the uplink path in this case.
- SNR signal to noise ratio
- the HPA is always operated in saturation and that the signal power from the uplink station is high enough in level at the satellite.
- the satellite operator is forced to monitor regularly the power flux density as received at the satellite transponder input.
- the aim is that the video signal from the uplink station is strong enough so that under clear weather conditions, the HPA on board of the satellite is driven in saturation with the DLA in linear mode. This criterion must also be met if the HPA transfer curve has changed due to aging.
- the uplink power is not accurately known (for instance if the uplink is not done from a site belonging to the satellite operator itself), the operating point of the high power amplifier cannot be determined only from monitoring the downlink power. On one hand this is due to the fact that close to saturation, the input power may vary by a few dB, while the output power will only vary at most a few tenth of dB. On the other hand, if a certain amount of downlink power is measured, it cannot be determined whether the HPA is operated below or above saturation because the transfer curve is ambiguous in output power.
- the bitrate of the telemetry data stream may contain a maximum of a few kbit/s. Therefore, even if the satellite is equipped with a power monitoring system, it is also preferable to perform measurements from a ground station instead of onboard the satellite, for many reasons (i.e. failure, weight of the satellite etc.).
- IOT In Orbit Tests
- a first conventional method as decribed in International Journal of Satellite Communications, Special issue on In-orbit Testing of Communications Satellites, Volume 13, Number 5, Wiley 1995 or in DE-C-33 33 418, is known as AM nulling according to which an amplitude modulated (AM) signal in the uplink is used which is swept in power until the amplitude modulation disappears completely. This point is exactly at saturation.
- a second conventional method of determining the transfer curve of the HPA consists of measuring transmit and receive power of a clean carrier, where all path attenuations have to be cancelled out. Both IOT measurement methods require that the transponder under test is not operated. In other words, the payload signal has to be switched off during the tests.
- a method for determining the operating point of a non-linear amplifier of a communication channel wherein a first signal is transmitted simultaneously with a second signal through said communication channel and said operating point of said non-linear amplifier is determined on the basis of an output signal of said communication channel corresponding to said second signal, the input power of said first signal being such that said non-linear amplifier is operated in a non-linear mode and the input power of said second signal being below the input power of said first signal.
- the level of said second signal is approx. 20 dB or more below the level of said first signal.
- said second signal is a pseudo noise modulated clean carrier signal and said output signal of said communication channel ( 1 ) corresponding to said second signal is a recovered carrier signal.
- said second signal is a clean carrier signal and wherein said output signal of said communication channel corresponding to said second signal is a narrowband filtered carrier signal.
- reference values are used together with said output signal of said communication channel corresponding to said second signal to determine the operating point of said non-linear amplifier.
- an apparatus for determining the operating point of a non-linear amplifier of a communication channel comprising means for transmitting a second signal through said communication channel simultaneously with a first signal being transmitted through said communication channel and means for determining said operating point of said non-linear amplifier on the basis of an output signal of said communication channel corresponding to said second signal, the input power of said first signal being such that said non-linear amplifier is operated in a non-linear mode and the input power of said second signal being below the input power of said first signal.
- said means for determining said operating point of said non-linear amplifier on the basis of an output signal of said communication channel corresponding to said second signal comprise means for storing reference values to be used together with said output signal of said communication channel corresponding to said second signal to determine the operating point of said non-linear amplifier.
- a first input signal is transmitted through the communication channel at a power level which drives the non-linear amplifier in a non-linear operation mode.
- a second input signal is transmitted through the communication channel simultaneously with the first input signal.
- the second input signal is transmitted at a level below the level of the first input signal. If the contribution of the second input signal to the total input of the non-linear amplifier is small, the operating point of the non-linear amplifier is determined almost only by the first input signal. Therefore, the output power corresponding to the second signal is determined most strongly by the input power of the first signal.
- the operating point of said non-linear amplifier is determined on the basis of an output signal of said communication channel corresponding to said second signal.
- the invention further provides a method for determining the operating point of a non-linear amplifier of a communication channel through which a payload signal is transmitted at a predetermined level, comprising: generating a first pseudo noise signal PN(t); modulating a clean carrier signal f(t) with said first pseudo noise signal PN(t) to generate a PN modulated clean carrier signal s(t); transmitting said PN modulated clean carrier signal s(t) simultaneously with said payload signal through said communication channel at a level below the level of said payload signal; receiving a receive signal s′(t) corresponding to said PN modulated clean carrier signal s(t) after having traveled through said communication channel; correlating said receive signal s′(t) with said first pseudo noise signal PN(t) to generate a recovered carrier signal f′(t); and determining the operating point of said non-linear amplifier of the communication channel on the basis of said clean carrier signal f(t) and said recovered carrier signal f′(t).
- the level of said PN modulated clean carrier signal s(t) is approx. 20 dB or even approx. 30 dB or more below the level of said payload signal.
- said first pseudo noise signal PN(t) is a binary pseudo noise sequence, said binary pseudo noise sequence being generated by means of a feed back shift register or a memory device in which a sequence of values of a pseudo noise signal is stored.
- Said correlating of said receive signal s′(t) and said first pseudo noise signal PN(t) can be achieved by delaying said first pseudo noise signal PN(t) and multiplying the delayed first pseudo noise signal PN(t) and said receive signal s′(t).
- a gain is determined on the basis of said clean carrier signal f(t) and said recovered carrier signal f′(t) and said gain is used to determine the input power of said payload signal.
- Reference values are used to derive from said gain the input power of said payload signal, said reference values having been pre-recorded for said non-linear amplifier and representing a gain curve or transfer curve of said non-linear amplifier over the input power of said payload signal.
- the method according to the invention is advantageously applicable if said communication channel is a transponder of a communication satellite.
- the invention furthermore provides an apparatus for determining the operating point of a non-linear amplifier of a communication channel through which a payload signal is transmitted at a predetermined level, comprising first pseudo noise signal generating means for generating a pseudo noise signal PN(t); first modulating means for modulating a clean carrier signal f(t) with said first pseudo noise signal PN(t) to generate a PN modulated clean carrier signal s(t); transmitting means for transmitting said PN modulated clean carrier signal s(t) simultaneously with said payload signal through said communication channel at a level below the level of said payload signal; receiving means for receiving a receive signal s′(t) corresponding to said PN modulated clean carrier signal s(t) after having traveled through said communication channel; and first correlating means for correlating said receive signal s′(t) with said pseudo noise signal PN(t) to generate a recovered carrier signal f′(t).
- the level of said PN modulated clean carrier signal s(t) is at least 20 dB or even at least 30 dB below the level of said payload signal.
- said first pseudo noise signal generating means ( 9 ) is a feed back shift register or a memory device in which a sequence of values of a pseudo noise signal is stored.
- a clean carrier signal f(t) is modulated with a pseudo noise signal PN(t) and transmitted through the communication channel at a level below the level of a payload signal which is transmitted via the communication channel simultaneously.
- the received signal s′(t) is correlated with the same pseudo noise signal PN(t) to obtain a recovered carrier signal f′(t).
- the power of the clean carrier signal f(t) and of the recovered carrier signal f′(t) are used to determine the gain of the signal and on the basis of reference values (calibration curves) the input power of the payload signal. Since the PN modulated clean carrier signal s(t) is transmitted at a low level, it is possible to perform measurements without switching off the payload signal, the input power of which defining the operating point of the non-linear amplifier.
- An important advantage of the method and the apparatus according to the invention is of course that the payload signal does not have to be switched off for performing the measurements. This limits considerably the downtime required for maintenance and verification of the communication channel, and thus increases availability of services.
- FIG. 1 shows a schematic diagram of a communication channel comprising a non-linear amplifier
- FIG. 2 shows transfer curves of a non-linear amplifier
- FIG. 3 shows a diagram of gain difference over input power of a non-linear amplifier
- FIG. 4 shows a schematic diagram of a transponder of a communication satellite
- FIG. 5 shows a schematic diagram of an embodiment of an apparatus according to the invention.
- FIGS. 6 a and 6 b show transfer curves and gain curves of a non-linear amplifier for large and small signals.
- FIG. 1 shows a communication channel 1 comprising a non-linear amplifier 2 for amplifying the signals transmitted through the communication channel. If a total input signal I is fed to an input 3 of the communication channel 1 , the signal traveles through the communication channel 1 , is amplified by the non-linear amplifier 2 , and is output as a total output signal O at an output 4 of the communication channel 1 .
- FIG. 2 which shows a transfer curve A of a traveling wave tube amplifier (TWTA), as an example of a non-linear amplifier
- TWTA traveling wave tube amplifier
- a non-linear mode of operation is effected if the input power P I of the total input signal I is high enough to operate the non-linear amplifier in the non-linear region (a) of its transfer curve.
- the goal is to drive the non-linear amplifier 2 in its saturation point as indicated by S in FIG. 2 to obtain maximum output power.
- each operating point of the non-linear amplifier in the non-linear region (a) is defined by a specific input power P I of an input signal I and a corresponding output power P o of an output signal O of the communication channel. In saturation the input signal provides an input power of P IS corresponding to an output power of P OS .
- a first input signal I 1 is transmitted through the communication channel 1 at a power level P I1 which drives the non-linear amplifier 2 in a non-linear operation mode.
- a second input signal i 2 is transmitted through the communication channel 1 simultaneously with the first input signal I 1 .
- the second input signal i 2 is transmitted at a level below the level of the first input signal I 1 .
- the input power P I2 of the second signal i 2 is lower than the input power P I1 of the first signal I 1 . If the contribution of the second input signal i 2 to the total input of the non-linear amplifier is small, the operating point of the non-linear amplifier is determined almost only by the first input signal.
- the output power P o2 corresponding to the second signal i 2 is determined most strongly by the input power P I1 of the first signal I 1 .
- any variation in input power of the first signal causes a variation in output power of the second signal.
- the second input signal should be some 15 to 30 dB or more, depending on the application, below the first input signal. This is indicated in the linear region (b) in FIG. 2 which shows a transfer curve B representing the output power of a small input signal plotted against the input power of a large input signal.
- the transfer curve B of the second input signal falls off much faster than the transfer curve of the first input signal so that any variation of the output power of the second input signal caused by a variation of the input power of the first input signal can be measured much easier as long as the part o 2 of the output signal O corresponding to the second input signal i 2 can be separated from the part O 1 of the output signal O corresponding to the first input signal I 1 , as indicated in FIG. 1 .
- the separation of the contributions O 1 and o 2 of the first and second input signals I 1 and i 2 , respectively, in the output signal O may be achieved in several different ways.
- the first input signal I 1 is a FM or QPSK signal
- the second input signal i 2 may be a pseudo noise modulated clean carrier signal as will be explained further below in greater detail.
- the recovered carrier signal represents the output signal o 2 corresponding to the second input signal i 2 .
- the second input signal could be a clean carrier signal having a frequency which avoids deterioration of the second input signal by the first input signal, for example having a frequency outside the frequency band of the first input signal.
- narrowband filtering the output signal O at the frequency of the second input signal the part o 2 of the second input signal i 2 in the total output signal O can be determined.
- the operating point of the non-linear amplifier can be determined in different ways. If the input power of the first and second input signal is known the output power corresponding to these signals can be measured and a transfer curve or a gain curve, an example being shown in FIG. 6 b , can be obtained. If the transfer curve or the gain curve is known, the input power of the first input signal driving the non-linear amplifier in a non-linear mode of operation can be determined by transmitting a second input signal of a known input power through the communication channel and measuring the output power corresponding to the second input signal.
- the input power of the first signal and, therefore, the operating point of the non-linear amplifier can be determined on the basis of the input power of the second input signal and the transfer curve or the gain curve (or any other representation of the above described relation between the large and the small input signal), if the second input signal is a small signal compared to the first input signal, as explained above.
- the transfer curve B of the second signal i 2 allows to determine the input power of the first signal I 1 to be P I1a without measuring the output power of the first signal at all.
- the transfer curve and the gain curve of the non-linear amplifier may change due to aging.
- such a change of the transfer curve can be detected by determining the operating point of the non-linear amplifier on the basis of first and second input signals I 1 and i 2 the individual input powers P I1 , and P I2 of which are known.
- the operating point can be determined and compared to the operating point derived on the basis of the transfer curve (or any other representation thereof).
- FIG. 3 shows a diagram representing a gain difference between the first signal and the second signal, i.e. gain small -gain large , plotted over the input power of the first signal.
- FIG. 4 shows the components of a transponder in a communication satellite as an example for a communication channel.
- An output signal of said receiving antenna 11 is fed to an input demultiplexer (IMUX) 13 after frequency conversion in frequency converter 12 .
- Said input demultiplexer 13 comprises several first filters 14 - 1 to 14 - n for separating individual signals within the signal from the antenna. Typically, one filter is provided for each signal to be separated from the other signals received via said receiving antenna 1 and corresponds to a communication channel.
- the n output signals of said input demultiplexer 13 are fed to a corresponding number of driver limiter amplifiers 15 a - 1 to 15 a - n and high power amplifiers 15 b - 1 to 15 b - n .
- a traveling wave tube TWT
- the high power amplifiers 15 b - 1 to 15 b - n are non-linear amplifiers having a transfer curve and gain curve as indicated by curves A in FIGS. 6 a and 6 b , respectively.
- the driver limiter amplifiers 15 a - 1 to 15 a - n are either limiting or amplifying the input signal received from the input demultiplexer 13 before being fed to the respective high power amplifier.
- the amplifier output signals are passed through second filters 16 - 1 to 16 - n which are part of an output multiplexer (OMUX) 17 combining the n amplifier output signals.
- the output signal of said output multiplexer 17 is fed to a transmitting antenna 18 for being transmitted to the desired area on the ground.
- each of said high power amplifiers 15 b - 1 to 15 b - n depends on the payload signal (the first input signal) from the uplink ground station, which signal should be such that the amplifier is driven in saturation in order to achieve maximum output power.
- the driver limiter amplifiers 15 a - 1 to 15 a - n can be set such that each of said high power amplifiers is operated in its saturation point. For the measurement described below the driver limiter amplifiers are set to linear operation.
- a pseudo noise signal PN(t) is generated by means of a pseudo noise signal generator 19 , for example a feed back shift register or a memory device in which a sequence of values of a pseudo noise signal is stored.
- the pseudo noise signal PN(t) has a very sharp autocorrelation function at zero delay. This allows to determine the time delay between the locally generated pseudo noise signal PN(t) and a received signal which is delayed due to the propagation time.
- the transponder remains usable during the test and can be continuously supplied with a payload signal.
- the level of the transmitted PN modulated clean carrier signal s(t) is sufficiently below the level of the payload signal, for example about 20 to 30 dB or more, such that the payload signal is not notably deteriorated.
- the PN modulated clean carrier signal s(t) can be transmitted while the communication channel is in use, i.e. simultaneously with a payload signal being transmitted to the transponder of the satellite from the same or from another ground station.
- antenna 23 is also used to receive the signal re-transmitted by the transponder of the satellite, in other words the signal which has traveled through the communication channel.
- the output signal of antenna 23 is passed through a downconverter 24 to obtain a receive signal s′(t) which is fed to a second multiplier 25 receiving also the same but delayed pseudo noise signal PN(t).
- the delay is generated by delaying means 26 which are set such that the output of the second multiplier 25 becomes maximum.
- the receive signal s′(t) is multiplied, in other words correlated with the very same pseudo noise signal PN(t) which has been used for generating the PN modulated clean carrier signal s(t) and a recovered carrier signal f′(t) is obtained which is only delayed and attenuated in comparison with the clean carrier signal f(t)
- the path attenuation is constant as free space loss does practically not vary with the distance between the satellite and the ground station. Since atmosperical attenuation can be measured with radiometers, it can be taken into account as well as the gain of the ground station antenna at the corresponding frequencies.
- the input power of the clean carrier signal f(t) and the output power of the recovered carrier signal f′(t) can be measured to determine the gain of this signal.
- the input power of the payload signal is determined on the basis of said gain and of reference values or calibration curves, which are shown in FIGS. 6 a and 6 b and which will be explained in greater detail further below.
- the gain of the small signal is measured to be ⁇ 4 dB the input power of the large signal is ⁇ 1 dB.
- this measurement is compared to measuring the output power: while the output power of the large signal changes by less than 0.05 dB for the input power varying from 0 dBW to ⁇ 1 dB, the gain of the small signal varies by almost 2 dB.
- FIG. 6 a transfer curves for a large signal (A) and three small signals (B 1 , B 2 , B 3 ) over a traveling wave tube amplifier (TWTA) are shown.
- TWTA traveling wave tube amplifier
- the values are given relative to the saturation point of the amplifier.
- the three small signals (B 1 , B 2 , B 3 ) are 20 dB, 30 dB, and 40 dB below the large signal, respectively.
- gain curves for the large signal (A) and the three small signals (B 1 , B 2 , B 3 ) are shown. Again, the values are given relative to the saturation point of the amplifier so that in FIG.
- a large signal and a small signal are generated where the small signal is for example 20 dB, 30 dB, or 40 dB below the large signal.
- the large and the small signal may be a clean carrier or the large signal may be a FM or OPSK modulated signal to come as close as possible to real operation conditions and the small signal may be a pseudo noise modulated clean carrier signal.
- Both signals, i.e. the large and the small signal are combined and transmitted to the transponder.
- the total input signal received by antenna 11 is fed to the input of the high power amplifier (TWTA).
- TWTA high power amplifier
- the combined signal is swept in power, thus the level difference between the large signal and the small signal at the input will always remain the same.
- the power of the small signal may be kept constant as it does not substantially influence the operating point of the non-linear amplifier.
- the output signal of the high power amplifier (TWTA) is fed to antenna 18 via output multiplexer 17 and the output levels corresponding to both input signals are measured separately.
- the output power of the large signal (which is almost equal to the total output power as the small signal has a negligible contribution) is given as a function of the input power of the large signal.
- the output power of the small signal is also given as a function of the input power of the large signal.
- the gain of the large signal and the gain of the small signals are given as a function of the input power of the large signal.
- means 27 for determining a gain on the basis of said clean carrier signal f(t) and said recovered carrier signal f′(t) are provided, receiving both the clean carrier signal f(t) and the recovered carrier signal f′(t). Furthermore, means 28 for deriving the input power of said payload signal from reference values and from said gain are provided. The output of said means 27 for determining a gain are supplied to said means 28 for deriving the input power of said payload signal.
- the reference values are stored in and supplied from means 29 for storing said reference values. The said reference values have been pre-recorded for said non-linear amplifier and represent a gain curve or transfer curve of said non-linear amplifier over the input power of said payload signal, as described with respect to FIGS. 6 a and 6 b.
- true noise signals can be used in the method and the apparatus according to the invention. Properties of true and pseudo noise signals are well known to those skilled in the art and are described, for example in Bernard Sklar, “Digital Communications—Fundamentals and Applications”, Prentice Hall, 1988.
Abstract
Description
Claims (40)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97122420 | 1997-12-18 | ||
EP97122420A EP0929164B1 (en) | 1997-12-18 | 1997-12-18 | Method and apparatus for determining an operating point of a non-linear amplifier of a communication channel |
Publications (1)
Publication Number | Publication Date |
---|---|
US6275678B1 true US6275678B1 (en) | 2001-08-14 |
Family
ID=8227830
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/213,557 Expired - Lifetime US6275678B1 (en) | 1997-12-18 | 1998-12-17 | Method and apparatus for determining an operating point of a non-linear amplifier of a communication channel |
Country Status (23)
Country | Link |
---|---|
US (1) | US6275678B1 (en) |
EP (1) | EP0929164B1 (en) |
JP (1) | JP3639531B2 (en) |
KR (1) | KR100609315B1 (en) |
CN (1) | CN1136682C (en) |
AR (1) | AR008353A1 (en) |
AT (1) | ATE190785T1 (en) |
AU (1) | AU741481B2 (en) |
BR (1) | BR9813708B1 (en) |
CA (1) | CA2315053C (en) |
DE (1) | DE69701473T2 (en) |
DK (1) | DK0929164T3 (en) |
EA (1) | EA002214B1 (en) |
ES (1) | ES2145552T3 (en) |
GR (1) | GR3033472T3 (en) |
HK (1) | HK1021455A1 (en) |
ID (1) | ID24961A (en) |
IL (1) | IL136765A (en) |
NO (1) | NO323273B1 (en) |
PL (1) | PL190186B1 (en) |
PT (1) | PT929164E (en) |
TR (1) | TR200001780T2 (en) |
WO (1) | WO1999033203A1 (en) |
Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020094015A1 (en) * | 1999-06-18 | 2002-07-18 | Societe Europeenne Des Satellites S.A. | Method and apparatus for determining characteristics of components of a communication channel |
US20020158619A1 (en) * | 2001-04-27 | 2002-10-31 | Chen Ernest C. | Satellite TWTA on-line non-linearity measurement |
US6535546B1 (en) * | 1997-12-18 | 2003-03-18 | Societe Europeenne Des Satellites S.A. | Method and apparatus for determining characteristics of components of a communication channel under load |
KR20030024285A (en) * | 2001-09-17 | 2003-03-26 | 한국전자통신연구원 | Operating Point Determination Apparatus and method for High Power Amplifier of Communication and Broadcasting Satellite Transponder |
US20040136469A1 (en) * | 2001-04-27 | 2004-07-15 | Weizheng Wang | Optimization technique for layered modulation |
US20040184521A1 (en) * | 2001-04-27 | 2004-09-23 | Chen Ernest C. | Equalizers for layered modulated and other signals |
US20050175119A1 (en) * | 2004-02-09 | 2005-08-11 | Worley David A. | Forward link quality link monitoring apparatus and method |
US20060013333A1 (en) * | 2001-04-27 | 2006-01-19 | The Directv Group, Inc. | Maximizing power and spectral efficiencies for layered and conventional modulations |
US20060022747A1 (en) * | 2002-10-25 | 2006-02-02 | The Directv Group, Inc. | Estimating the operating point on a non-linear traveling wave tube amplifier |
US20060056541A1 (en) * | 2002-07-01 | 2006-03-16 | Chen Ernest C | Improving hierarchical 8psk performance |
US20060153315A1 (en) * | 2001-04-27 | 2006-07-13 | Chen Ernest C | Lower complexity layered modulation signal processor |
US20060153314A1 (en) * | 2002-10-25 | 2006-07-13 | Chen Ernest C | Method and apparatus for tailoring carrier power requirements according to availability in layered modulation systems |
US7151807B2 (en) | 2001-04-27 | 2006-12-19 | The Directv Group, Inc. | Fast acquisition of timing and carrier frequency from received signal |
US7173981B1 (en) | 2001-04-27 | 2007-02-06 | The Directv Group, Inc. | Dual layer signal processing in a layered modulation digital signal system |
US7209524B2 (en) | 2001-04-27 | 2007-04-24 | The Directv Group, Inc. | Layered modulation for digital signals |
US7245671B1 (en) | 2001-04-27 | 2007-07-17 | The Directv Group, Inc. | Preprocessing signal layers in a layered modulation digital signal system to use legacy receivers |
US7738587B2 (en) | 2002-07-03 | 2010-06-15 | The Directv Group, Inc. | Method and apparatus for layered modulation |
US7822154B2 (en) | 2001-04-27 | 2010-10-26 | The Directv Group, Inc. | Signal, interference and noise power measurement |
US8005035B2 (en) | 2001-04-27 | 2011-08-23 | The Directv Group, Inc. | Online output multiplexer filter measurement |
US20120112925A1 (en) * | 2010-11-08 | 2012-05-10 | Electronics And Telecomunications Research Institute | Apparatus and method for monitoring status of satellite transponder using statistical analysis of telemetry data |
US8208526B2 (en) | 2001-04-27 | 2012-06-26 | The Directv Group, Inc. | Equalizers for layered modulated and other signals |
US8259641B2 (en) | 2001-04-27 | 2012-09-04 | The Directv Group, Inc. | Feeder link configurations to support layered modulation for digital signals |
WO2017130071A1 (en) * | 2016-01-25 | 2017-08-03 | Valens Semiconductor Ltd. | Utilizing known data for status signaling |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100488347B1 (en) | 2002-10-31 | 2005-05-10 | 삼성전자주식회사 | Siloxane-based resin and method for forming an insulating thin film between interconnect layers in a semiconductor device by using the same |
AU2004218611B2 (en) * | 2003-10-10 | 2007-03-08 | The Directv Group, Inc. | Coherent averaging for measuring traveling wave tube amplifier nonlinearity |
CA2708503C (en) * | 2007-12-21 | 2016-10-25 | Astrium Limited | Multiport amplifiers in communications satellites |
WO2011144620A1 (en) * | 2010-05-17 | 2011-11-24 | Inradios Integrated Radio Solutions Gmbh | Assembly and method for the parallel processing of data streams by means of satellite communication connections |
Citations (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4168398A (en) * | 1976-11-10 | 1979-09-18 | Nippon Electric Co., Ltd. | Initial acquisition signal detection system for TDMA satellite communication |
DE3333418A1 (en) | 1983-09-16 | 1985-04-04 | ANT Nachrichtentechnik GmbH, 7150 Backnang | Method for determining the saturation power of a satellite power amplifier |
US4637017A (en) | 1984-05-21 | 1987-01-13 | Communications Satellite Corporation | Monitoring of input backoff in time division multiple access communication satellites |
US4896369A (en) | 1984-12-28 | 1990-01-23 | Harris Corporation | Optimal satellite TWT power allocation process for achieving requested availability and maintaining stability in ALPC-type networks |
JPH03139027A (en) | 1989-10-24 | 1991-06-13 | Fujitsu Ltd | Transmission power control system in satellite communication |
US5204898A (en) * | 1990-08-03 | 1993-04-20 | Laboratoire Europeen De Recherches Electroniques Avancees Sociate En Nom Collectif | Method of protection against the unauthorized unscrambling of scrambled television broadcasts, and implementation method |
US5455960A (en) * | 1992-01-16 | 1995-10-03 | Harris Corporation | Low-power access technique for certain satellite transponders |
US5568407A (en) * | 1995-01-03 | 1996-10-22 | International Business Machines Corporation | Method and system for the design verification of logic units and use in different environments |
US5623227A (en) * | 1995-10-17 | 1997-04-22 | Motorola, Inc. | Amplifier circuit and method of controlling an amplifier for use in a radio frequency communication system |
US5635870A (en) * | 1995-08-15 | 1997-06-03 | David; Michael | Efficient amplification techniques for non-linear amplifiers |
US5720039A (en) * | 1995-09-01 | 1998-02-17 | Cd Radio, Inc. | Satellite multiple access system with distortion cancellation and compression compensation |
US5731993A (en) * | 1996-09-09 | 1998-03-24 | Hughes Electronics | Nonlinear amplifier operating point determination system and method |
US5732334A (en) * | 1996-07-04 | 1998-03-24 | Mitsubishi Denki Kabushiki Kaisha | Radio transmitter and method of controlling transmission by radio transmitter |
US5926753A (en) * | 1996-06-27 | 1999-07-20 | Nec Corporation | Radio selection call receiver capable of increasing receiving ratio |
US5940025A (en) * | 1997-09-15 | 1999-08-17 | Raytheon Company | Noise cancellation method and apparatus |
US5987304A (en) * | 1996-05-31 | 1999-11-16 | Allgon Ab | Repeater with variable bandwidth |
-
1997
- 1997-12-18 AT AT97122420T patent/ATE190785T1/en active
- 1997-12-18 ES ES97122420T patent/ES2145552T3/en not_active Expired - Lifetime
- 1997-12-18 DE DE69701473T patent/DE69701473T2/en not_active Expired - Lifetime
- 1997-12-18 PT PT97122420T patent/PT929164E/en unknown
- 1997-12-18 EP EP97122420A patent/EP0929164B1/en not_active Expired - Lifetime
- 1997-12-18 DK DK97122420T patent/DK0929164T3/en active
-
1998
- 1998-12-17 JP JP2000525993A patent/JP3639531B2/en not_active Expired - Lifetime
- 1998-12-17 BR BRPI9813708-5A patent/BR9813708B1/en not_active IP Right Cessation
- 1998-12-17 ID IDW20001365A patent/ID24961A/en unknown
- 1998-12-17 KR KR1020007006749A patent/KR100609315B1/en not_active IP Right Cessation
- 1998-12-17 IL IL13676598A patent/IL136765A/en not_active IP Right Cessation
- 1998-12-17 PL PL98341217A patent/PL190186B1/en unknown
- 1998-12-17 CN CNB988130351A patent/CN1136682C/en not_active Expired - Lifetime
- 1998-12-17 CA CA002315053A patent/CA2315053C/en not_active Expired - Lifetime
- 1998-12-17 TR TR2000/01780T patent/TR200001780T2/en unknown
- 1998-12-17 AU AU25134/99A patent/AU741481B2/en not_active Expired
- 1998-12-17 US US09/213,557 patent/US6275678B1/en not_active Expired - Lifetime
- 1998-12-17 EA EA200000669A patent/EA002214B1/en not_active IP Right Cessation
- 1998-12-17 WO PCT/EP1998/008306 patent/WO1999033203A1/en active IP Right Grant
- 1998-12-18 AR ARP980106507A patent/AR008353A1/en active IP Right Grant
-
2000
- 2000-01-12 HK HK00100189A patent/HK1021455A1/en not_active IP Right Cessation
- 2000-05-22 GR GR20000401168T patent/GR3033472T3/en unknown
- 2000-06-16 NO NO20003158A patent/NO323273B1/en not_active IP Right Cessation
Patent Citations (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4168398A (en) * | 1976-11-10 | 1979-09-18 | Nippon Electric Co., Ltd. | Initial acquisition signal detection system for TDMA satellite communication |
DE3333418A1 (en) | 1983-09-16 | 1985-04-04 | ANT Nachrichtentechnik GmbH, 7150 Backnang | Method for determining the saturation power of a satellite power amplifier |
US4637017A (en) | 1984-05-21 | 1987-01-13 | Communications Satellite Corporation | Monitoring of input backoff in time division multiple access communication satellites |
US4896369A (en) | 1984-12-28 | 1990-01-23 | Harris Corporation | Optimal satellite TWT power allocation process for achieving requested availability and maintaining stability in ALPC-type networks |
JPH03139027A (en) | 1989-10-24 | 1991-06-13 | Fujitsu Ltd | Transmission power control system in satellite communication |
US5204898A (en) * | 1990-08-03 | 1993-04-20 | Laboratoire Europeen De Recherches Electroniques Avancees Sociate En Nom Collectif | Method of protection against the unauthorized unscrambling of scrambled television broadcasts, and implementation method |
US5455960A (en) * | 1992-01-16 | 1995-10-03 | Harris Corporation | Low-power access technique for certain satellite transponders |
US5568407A (en) * | 1995-01-03 | 1996-10-22 | International Business Machines Corporation | Method and system for the design verification of logic units and use in different environments |
US5635870A (en) * | 1995-08-15 | 1997-06-03 | David; Michael | Efficient amplification techniques for non-linear amplifiers |
US5720039A (en) * | 1995-09-01 | 1998-02-17 | Cd Radio, Inc. | Satellite multiple access system with distortion cancellation and compression compensation |
US5623227A (en) * | 1995-10-17 | 1997-04-22 | Motorola, Inc. | Amplifier circuit and method of controlling an amplifier for use in a radio frequency communication system |
US5987304A (en) * | 1996-05-31 | 1999-11-16 | Allgon Ab | Repeater with variable bandwidth |
US5926753A (en) * | 1996-06-27 | 1999-07-20 | Nec Corporation | Radio selection call receiver capable of increasing receiving ratio |
US5732334A (en) * | 1996-07-04 | 1998-03-24 | Mitsubishi Denki Kabushiki Kaisha | Radio transmitter and method of controlling transmission by radio transmitter |
US5731993A (en) * | 1996-09-09 | 1998-03-24 | Hughes Electronics | Nonlinear amplifier operating point determination system and method |
US5940025A (en) * | 1997-09-15 | 1999-08-17 | Raytheon Company | Noise cancellation method and apparatus |
Cited By (31)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6535546B1 (en) * | 1997-12-18 | 2003-03-18 | Societe Europeenne Des Satellites S.A. | Method and apparatus for determining characteristics of components of a communication channel under load |
US6934314B2 (en) * | 1999-06-18 | 2005-08-23 | Ses Astra S.A. | Method and apparatus for determining characteristics of components of a communication channel |
US20020094015A1 (en) * | 1999-06-18 | 2002-07-18 | Societe Europeenne Des Satellites S.A. | Method and apparatus for determining characteristics of components of a communication channel |
US7706466B2 (en) | 2001-04-27 | 2010-04-27 | The Directv Group, Inc. | Lower complexity layered modulation signal processor |
US8005035B2 (en) | 2001-04-27 | 2011-08-23 | The Directv Group, Inc. | Online output multiplexer filter measurement |
US20040184521A1 (en) * | 2001-04-27 | 2004-09-23 | Chen Ernest C. | Equalizers for layered modulated and other signals |
US8259641B2 (en) | 2001-04-27 | 2012-09-04 | The Directv Group, Inc. | Feeder link configurations to support layered modulation for digital signals |
US20020158619A1 (en) * | 2001-04-27 | 2002-10-31 | Chen Ernest C. | Satellite TWTA on-line non-linearity measurement |
US20060013333A1 (en) * | 2001-04-27 | 2006-01-19 | The Directv Group, Inc. | Maximizing power and spectral efficiencies for layered and conventional modulations |
US8208526B2 (en) | 2001-04-27 | 2012-06-26 | The Directv Group, Inc. | Equalizers for layered modulated and other signals |
US20040136469A1 (en) * | 2001-04-27 | 2004-07-15 | Weizheng Wang | Optimization technique for layered modulation |
US20060153315A1 (en) * | 2001-04-27 | 2006-07-13 | Chen Ernest C | Lower complexity layered modulation signal processor |
US7778365B2 (en) | 2001-04-27 | 2010-08-17 | The Directv Group, Inc. | Satellite TWTA on-line non-linearity measurement |
US7151807B2 (en) | 2001-04-27 | 2006-12-19 | The Directv Group, Inc. | Fast acquisition of timing and carrier frequency from received signal |
US7920643B2 (en) | 2001-04-27 | 2011-04-05 | The Directv Group, Inc. | Maximizing power and spectral efficiencies for layered and conventional modulations |
US7173981B1 (en) | 2001-04-27 | 2007-02-06 | The Directv Group, Inc. | Dual layer signal processing in a layered modulation digital signal system |
US7184489B2 (en) | 2001-04-27 | 2007-02-27 | The Directv Group, Inc. | Optimization technique for layered modulation |
US7184473B2 (en) | 2001-04-27 | 2007-02-27 | The Directv Group, Inc. | Equalizers for layered modulated and other signals |
US7209524B2 (en) | 2001-04-27 | 2007-04-24 | The Directv Group, Inc. | Layered modulation for digital signals |
US7822154B2 (en) | 2001-04-27 | 2010-10-26 | The Directv Group, Inc. | Signal, interference and noise power measurement |
US7245671B1 (en) | 2001-04-27 | 2007-07-17 | The Directv Group, Inc. | Preprocessing signal layers in a layered modulation digital signal system to use legacy receivers |
KR20030024285A (en) * | 2001-09-17 | 2003-03-26 | 한국전자통신연구원 | Operating Point Determination Apparatus and method for High Power Amplifier of Communication and Broadcasting Satellite Transponder |
US20060056541A1 (en) * | 2002-07-01 | 2006-03-16 | Chen Ernest C | Improving hierarchical 8psk performance |
US7738587B2 (en) | 2002-07-03 | 2010-06-15 | The Directv Group, Inc. | Method and apparatus for layered modulation |
US7230480B2 (en) | 2002-10-25 | 2007-06-12 | The Directv Group, Inc. | Estimating the operating point on a non-linear traveling wave tube amplifier |
US7173977B2 (en) | 2002-10-25 | 2007-02-06 | The Directv Group, Inc. | Method and apparatus for tailoring carrier power requirements according to availability in layered modulation systems |
US20060153314A1 (en) * | 2002-10-25 | 2006-07-13 | Chen Ernest C | Method and apparatus for tailoring carrier power requirements according to availability in layered modulation systems |
US20060022747A1 (en) * | 2002-10-25 | 2006-02-02 | The Directv Group, Inc. | Estimating the operating point on a non-linear traveling wave tube amplifier |
US20050175119A1 (en) * | 2004-02-09 | 2005-08-11 | Worley David A. | Forward link quality link monitoring apparatus and method |
US20120112925A1 (en) * | 2010-11-08 | 2012-05-10 | Electronics And Telecomunications Research Institute | Apparatus and method for monitoring status of satellite transponder using statistical analysis of telemetry data |
WO2017130071A1 (en) * | 2016-01-25 | 2017-08-03 | Valens Semiconductor Ltd. | Utilizing known data for status signaling |
Also Published As
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6275678B1 (en) | Method and apparatus for determining an operating point of a non-linear amplifier of a communication channel | |
US5731993A (en) | Nonlinear amplifier operating point determination system and method | |
NO175510B (en) | Signal level amplifier for high frequency signals | |
JP4197869B2 (en) | Method and apparatus for determining device characteristics of a communication channel | |
KR100417168B1 (en) | Method and apparatus for determining characteristics of components of a communication channel under load | |
RU2627297C2 (en) | Method of characterizing orbital satellite transmitting antenna and appropriate system | |
US6728650B2 (en) | High power amplifier operating point determination apparatus and method for satellite communications system | |
JPH04372234A (en) | Transmission power control system | |
JPH02280424A (en) | Transmission power control system | |
CZ20002191A3 (en) | Process and apparatus for determining working point of communication channel non-linear amplifier | |
JPH11234185A (en) | Ground station and calibration device for equipment mounted on satellite | |
JP3038899B2 (en) | Automatic frequency / gain control circuit | |
KR0133336B1 (en) | Satelite reperater | |
JP2504214B2 (en) | Automatic Level Control Method for Micro Satellite Communication Equipment | |
JPH03139027A (en) | Transmission power control system in satellite communication | |
KR20050097828A (en) | Apparatus and method for real time determination of high power amplifier's output power level and it's operating point in satellite communication | |
JPS58200640A (en) | Controlling system of electric power for transmitting satellite communication | |
Bennett | Early Bird I communications parameters | |
JPH03101526A (en) | Satellite channel monitoring system | |
JP2788583B2 (en) | Receiving machine | |
KR20090031080A (en) | System for treating oscillation from relay system in wireless telecommunication system and method thereof | |
JPH0231528A (en) | Satellite repeater monitoring device | |
CZ20002192A3 (en) | Process and apparatus for determining properties of communication apparatus elements under load | |
JPS6313617B2 (en) | ||
JPH04239226A (en) | Transmission power control system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SOCIETE EUROPEENNE DES SATELLITES S.A., LUXEMBOURG Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BETHSCHEIDER, GERHARD;HARLES, GUY;REEL/FRAME:009834/0798 Effective date: 19990211 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
AS | Assignment |
Owner name: SES ASTRA S.A., LUXEMBOURG Free format text: CHANGE OF NAME;ASSIGNOR:SOCIETE EUROPEENE DES SATELLITES S.A.;REEL/FRAME:015583/0131 Effective date: 20011109 |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Free format text: PAYER NUMBER DE-ASSIGNED (ORIGINAL EVENT CODE: RMPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
FPAY | Fee payment |
Year of fee payment: 12 |